Research On Load Response Analysis And Operation Status Identification Method Of Lunar Regolith Drilling And Coring

Drilling & coring is the main method to obtain the extraterrestrial regolith with sequence information.The lunar regolith sample with continuous sequence information has great engineering value and scientific significance for the research of formation and evolution of the moon,the construction of lunar base and the utilization of lunar resources.The exploration missions about lunar regolith sampling and utilizing are being implemented in many countries throughout the world.Facing the challenges resulting from uncertain lunar regolith conditions,the design of the coring drill with excellent performance is developed,considering the matching design of its structure parameters for function design,sample mass in particular,in order to adapt to the different drilling conditions in which critical size particles randomly distributed in the lunar regolith.The research on identification method for lunar regolith and drilling strategy are carried out to interpret telemetry datas of lunar drilling and coring process and provide basic theoretical support for future lunar exploration missions.Based on the lunar regolith samples from Apollo missions,the researches of particle diameter size distribution and morophology along the lunar regolith profile are carried out with the variation of lunar regolith mechanical parameters with depth,like cohesion and internal friction angle.Facing the high sampling rate of lunar regolith and wide adaptability of drilling conditions for drilling and coring process,the matching design of the structural parameters of the coring drill for sampling fluency is completed,including the parameters design of the chip removal area,the variable inner diameter design of the sampling area and the seal design of the sampling area.Drilling load model for lunar regolith particles is developed based on the principles of rotary drilling cutting and screw chips removal.The influence of drilling loads response with lunar regolith particles and drilling critical size particles is analyzed with the verification of the interaction between coring drill and drilling critical size particles by discrete element simulation.Lunar soil simulant for drilling and coring experiments is constructed,especially the simulant with drilling critical size particles.Drilling and coring experiments are carried out by the drilling and coring test bed.The study on drilling loads response is carried out,which provides experimental basis for drilling parameters matching and lunar regolith identification.Considering the coring load response casued by lunar regolith particles and critical size particles,the load model of the flexible coring tube for lunar regolith particles and the interaction between critical size particles and coring mechanism on different area are carried out with verification by discrete element simulation.Coring load response experiments are proposed to analyze the influence caused by critical size particles during the drilling and coring process.Combined with the drilling and coring experiments,the coring load response of the coring drill is studied,which provides experimental basis for drilling parameters matching and lunar regolith identification.According to drill loads response in different drilling parameters and the characteristic of ground-moon information interaction and joint control of the drilling and coring system,an autonomous drilling strategy process based on drill loads is developed.Considering the drilling conditions by the critical size particles,lunar remote control strategy based on depth and time is proposed with the matching design of the motion parameters for drilling or coring conditions.A coring state identification model based on discrete Markov model with coring load characteristic is carried out.According to the telemetry data of drill loads from Chang’e-5,the stratification state interpretation of lunar regolith is carried out and the actual efficiency of the coring drill and control strategy from Chang’e-5 is analyzed.Through the research of this paper,the maching design of coring drill structure parameters can improve the fluency and mass rate of the lunar regolith sample and adaptability of critical size particles in the lunar regolith profile.The autonomous drilling strategy and identification model can analyze and interpret the drilling state based on lunar telemetry data.The performance of coring drill is better than Luna-24 coring drill in terms of sample mass,drills load response,ratio of sample diameter to drill sample,drilling strategy and lunar regolith particles adaptability,which can provide technical and theoretic support for future extraterrestrial drilling and sampling missions.